The present invention relates to a magnetic head apparatus with an IC chip to drive a thin film magnetic element used in, for example, a magnetic disk apparatus or the like and a magnetic disk apparatus having the magnetic head apparatus.
According to a magnetic disk apparatus, a magnetic head slider attached to a front end section of a suspension is made to fly from a surface of a rotating magnetic disk and under the state, recording to the magnetic disk and/or reproducing from the magnetic disk are carried out by a thin film magnetic head element mounted to the magnetic head slider.
With large capacity and high density recording of a magnetic disk apparatus in recent years, high data rate has been progressed and a constitution proposed as one of means for achieving the high data rate, is a structure in which a section of a drive circuit for the magnetic head element is formed with an IC chip and the IC chip is mounted on a suspension (chip on suspension structure). By adopting the structure, a wiring distance from the drive circuit to the magnetic head element is shortened and accordingly, unnecessary noise added to a head drive signal can be reduced, as a result, a recording characteristic in a high data rate is promoted. Further, a very weak signal outputted from a reading head element of a magnetoresistive effect (MR) type, can be amplified at a location more proximate to the MR type head element.
According to such IC chip, in view of its mounted structure, dimensions need to be very small, however, when the dimensions are reduced, a surface area of the IC chip is reduced by an amount of the reduced dimensions and heat radiation becomes insufficient. Further, since the IC chip must be mounted on a suspension having a small space and since at a high data rate up to 1 Gbps, parasitic impedance of a lead frame constituting a terminal when packaged, generates noise which effects adverse influence on electric performance, the IC chip assembly needs to be formed in a bare chip assembly. Therefore, heat radiation of the IC chip is further decreased. Moreover, considerably large current flows in the IC chip in recording operation and accordingly, the heat generation is much increased and therefore, insufficient heat radiation performance causes a serious problem.
Further, as a spring member of the suspension, there is normally used a leaf spring made of stainless steel, however, stainless steel is provided with low heat conductivity as a metal material and therefore, when the chip on suspension structure is adopted, cooling by heat radiation can not be so much expected.
In this way, according to a conventional magnetic head apparatus having the chip on suspension structure, there pose the following problems:
(1) Since the IC chip is very thin and small, an effective measure of heat radiation against the heat generation is difficult.
(2) Since the IC chip is mounted on the suspension on a side opposed to a magnet, it is difficult to attach a heat radiation structure directly to the IC chip per se.
(3) Since stainless steel used for the spring member of the suspension is provided with the low heat conductivity, the heat radiation cannot be carried out sufficiently by the normal chip on suspension structure.
A technology of mounting the IC chip not on the suspension but directly on a support arm (swing arm) for supporting the suspension is publicly known (for example, Japanese Utility Model Publication No. Sho. 56-9576, Japanese Patent Publication No. Sho. 62-197909, Japanese Patent Publication No. Hei. 3-187295). However, according to the structure for mounting the IC chip directly on the support arm, the respective support arm needs to be separately mounted with the suspension and the IC chip respectively and accordingly, there poses a problem that not only a number of integrating steps is increased and integrating steps are troublesome but also an integration time period is prolonged. Further, since the size of IC chip is further reduced and since the support arm is provided with a three-dimensional structure, it is significantly difficult to mount the IC chip directly on the respective support arm.
Further, caution is required in that the well-known technologies of mounting the IC chip on the support arm are technologies of mounting the packaged IC chip. According to the package IC chip, heat can be radiated from a lead frame and therefore, heat generation does not pose a serious problem. When the IC is mounted to a portion having a small space and when the IC chip is formed by a bare chip in order to deal with high data rate as in the IC chip according to the invention, the problem of heat generation is particularly posed.
The invention is for resolving the above-described problems of the conventional technologies and it is an object thereof to provide a magnetic head apparatus having a novel structure in which integration thereof is simple and heat radiation of an IC chip can further be expedited even when the IC chip is formed by a bare chip and a magnetic disk apparatus having the magnetic head apparatus.
According to the invention, there is provided a magnetic head apparatus characterized in comprising a magnetic head slider having at least one thin film magnetic head element, a suspension mounting the magnetic head slider on one face thereof, an IC chip mounted with a circuit for the thin film magnetic head element and a support arm for fixedly supporting the suspension, wherein the IC chip is mounted on the one face of the suspension and is thermally coupled to the support arm.
There is constructed a constitution in which the IC chip mounted with the circuit for the thin film magnetic head element is not directly mounted on the support arm but is mounted on the suspension and is thermally coupled with the support arm. By constituting in this way, a head gimbal assembly (HGA) may be formed by previously mounting the IC chip on the suspension, that is, by previously integrating the magnetic head slider and the IC chip on the suspension having traces and the HGA maybe attached to the support arm and therefore, the integration becomes very simple, a reduction in a number of integrating steps and shortening of integration time period are achieved, further, heat radiation is significantly expedited by conducting heat to the support arm and utilizing the support arm as a heat sink.
It is preferable that the IC chip is mounted to a vicinity of a section of the suspension fixedly attached to the support arm and the support arm is brought into contact with other face of the suspension at a section of the suspension mounted with the IC chip.
It is also preferable that the IC chip is mounted to a vicinity of a section of the suspension fixedly attached to the support arm and the support arm and the IC chip are thermally coupled directly via a member having a high heat conductivity. In this case, it is more preferable that the member having the high heat conductivity is brought into contact with a face of the suspension on a side opposed to a face of the suspension for mounting the IC chip.
It is also preferable that the suspension comprises a metal material including a material having a high heat conductivity, or the suspension is provided with a structure of laminating a material layer having a high heat conductivity on a metal member.
It is also preferable that the IC chip is mounted to the vicinity of the section of the suspension fixedly attached to the support arm and the support arm and the IC chip are thermally coupled via a through port provided at a spring member of the suspension. In this case, it is more preferable that the support arm and the IC chip are thermally coupled via only a resin layer of the suspension.